Vocabulary is a basic of a language it is very important to be mastered first. English is one of few the international language, many other used English language everywhere. English language is very important. Many methods to improve students vocabulary, one of them is use mnemonic method. The objective of this research entitled ‘’ teaching vocabulary using mnemonic method in sentences ‘’ to find out, whether mnemonic method in sentences improve for student’s vocabulary. The research method of this research is quantitative research method, or more specially used quasi experimental design with two group pretest and post-test. The population is the 1st grade of junior high school in MTS AL-BIDAYAH, Batujajar Bandung and the sample of the research are two class there are experimental and control class. The instrument of this research is multiple choicetest. The data of the research is collected by giving multiple choices to student sample. The collected data of this research are analyzing by SPSS program. And the result of the data analysis showed that the mean of experimental group is bigger than control group (77.4 > 62.5) and the data statistic T –test shows T-observe is bigger than t-table with degree of freedom (df) 67 and level of significant (0. 991 > 0.00). Based on the data analysis above, the alternative hypothesis is supported. In other word teaching vocabulary using mnemonic method in sentences is significance influence the student to improve student’s vocabulary mastery.